/**
 * @author xxt
 * @param {String} url 
 * @param {String} params 
 * @param {function} headersFn 
 * @return Promise
 */
function get(url,params,headersFn){
   return  new Promise((resolve,reject) =>{
    const xhr = new XMLHttpRequest
    xhr.onreadystatechange = function(){
     if(xhr.readyState ==4) {
         if(xhr.status == 200){
          let res = JSON.parse(xhr.responseText)
          resolve(res)
         }else{
          reject(xhr.status)
         }
     }
    }
    xhr.open('get',`${url}?${params}`)
    if(headersFn) headersFn(xhr)
    xhr.send(null)
 })
}

function post(url,params,headersFn){
    return  new Promise((resolve,reject) =>{
     const xhr = new XMLHttpRequest
     xhr.onreadystatechange = function(){
      if(xhr.readyState ==4) {
          if(xhr.status == 200){
           let res = JSON.parse(xhr.responseText)
           resolve(res)
          }else{
           reject(xhr.status)
          }
      }
     }
     xhr.open('post',url)
     xhr.setRequestHeader('content-type','application/x-www-form-urlencoded')
     if(headersFn) headersFn(xhr)
     xhr.send(params)
  })
 }
 









